Reliable data storage for decentralized computer systems

ABSTRACT

A method includes receiving a data object for storage in a storage system. The storage system includes a number of datacenters (s) interconnected by a first network. Each of the datacenters is located in a geographic location that is different than any geographic locations of any other of the datacenters. The method includes creating secondary copies of the data object. A number of secondary copies is equal to at least s−1. The method includes, in accordance with a placement map of at least one of the datacenters, storing a primary copy of the data object in one of the datacenters. The method also includes, in each other of the datacenters, storing at least one of the secondary copies. The method also includes monitoring, via a plurality of data monitors, an accessibility of data stored in the storage system. The data includes the primary copy and the secondary copies of the data objects.

TECHNICAL FIELD

This disclosure relates generally to reliable data storage fordecentralized systems and, more specifically, to reliable data storageusing lightweight datacenters.

BACKGROUND

Enterprise cloud computing may deploy in a few large datacenters. Thisapproach may offer economies of scale in centralizing operations,building supply lines, and focusing resources to harden physical plantsagainst failures, disasters, attacks, or other vulnerabilities. However,centralizing operations has performance costs, particularly for the manyusers remotely located from the few datacenters, which can introduceundesirable network latency.

One proposed solution to the performance and latency problems is the useof smaller, more geographically dispersed datacenters. However, it maybe cost prohibitive to invest the same resources to protect moredatacenters the same way large datacenters are protected. Thus, there isa need for providing more reliable data management when data is beingstored in datacenters that individually have lower reliability thantraditional, larger datacenters.

SUMMARY

In an aspect, this disclosure is directed to a method. The method mayinclude identifying a datacenter group having a number of datacenters(s). Each datacenter of the s datacenters may include a plurality ofdata monitors. A number of the plurality of data monitors in eachdatacenter may be equal to at least s+1. For each datacenter of thedatacenter group, the method may include creating a placement map. Themethod may also include receiving a data object to be stored in thedatacenter group. The method may include creating secondary copies ofthe data object. A number of the secondary copies may be equal to atleast s−1. The method may also include, in accordance with the placementmaps, storing a primary copy of the data object in one of thedatacenters. The method may also include, in each other of thedatacenters, storing at least one of the secondary copies. Eachdatacenter may be located at a geographic location that is differentthan a respective geographic location of the other datacenters of thedatacenter group.

According to another aspect, this disclosure is directed to a system.The system may include a first network and a total number of datacenters(s) interconnected via the first network. The system may include a datacontroller communicatively coupled to the first network. The datacontroller may include an input/output for communicating via a secondnetwork, a processor communicatively coupled to the input/output, andmemory storing instructions that cause the processor to effectuateoperations. The operations may include, for each datacenter of the sdatacenters, creating a placement map. The operations may also includereceiving a data object via the second network. The operations mayinclude creating secondary copies of the data object. A number ofsecondary copies may be equal to at least s−1. The operations may alsoinclude, in accordance with the placement maps, storing a primary copyof the data object in one of the datacenters. The operations may alsoinclude, in each of the other datacenters, storing at least one of thesecondary copies. Each of the s datacenters may located atgeographically distinct locations from one another.

In accordance with yet another aspect, this disclosure is directed to amethod. The method may include receiving a data object for storage in astorage system. The storage system may include a number of datacenters(s) interconnected by a first network. Each of the datacenters may belocated in a geographic location that is different than any geographiclocations of any other of the datacenters. The method may includecreating secondary copies of the data object. A number of secondarycopies may be equal to at least s−1. The method may include, inaccordance with a placement map of at least one of the datacenters,storing a primary copy of the data object in one of the datacenters. Themethod may also include, in each other of the datacenters, storing atleast one of the secondary copies. The method may also includemonitoring, via a plurality of data monitors, an accessibility of datastored in the storage system. The data may include the primary copy andthe secondary copies of the data objects.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the herein described systems and methods for network modelingand building, updating, and querying a graph database are described morefully with reference to the accompanying drawings, which provideexamples. In the following description, for purposes of explanation,numerous specific details are set forth in order to provide anunderstanding of the variations in implementing the disclosedtechnology. However, the instant disclosure may take many differentforms and should not be construed as limited to the examples set forthherein. Where practical, like numbers refer to like elements throughout.

FIG. 1 illustrates an exemplary network including data storage systems.

FIG. 2 is a flowchart of an exemplary method.

FIG. 3 illustrates an exemplary data storage system.

FIG. 4 illustrates a data flow for storing data within the data storagesystem.

FIG. 5 illustrates an exemplary method for responding to a query.

FIG. 6 illustrates an exemplary network device.

DETAILED DESCRIPTION

To increase data platform reliability, a platform provider may desire tominimize loss events that impact service (e.g., access to the data). Forexample, a loss event may include unavailability events, such as downtime of a service or inaccessibility of a service's data due to a host,power, switch, or datacenter failure. A loss event may also includepermanent loss of data, such as when all copies of a data object arelost, such as due to drive failures.

Platform reliability may be related to availability, which may bemeasured by the percentage of time that data is available to a service.For example, availability may be measured as “nines,” which refers tothe number of leading 9-digits in a decimal representation of thepercentage. Optionally the “nines” measurement may refer to the decimalrepresentation after rounding to a defined number of places. Forexample, “5 nines” may refer to 99.999% availability, while “threenines” may refer to 99.9% availability. (As a note, this availabilitymetric may be based on an assumption that all data is “recoverable” in afinite time one way or another, even if that recovery is paying apenalty without actually recovering that permanently lost data.)

Just as a whole platform may have reliability and availability metrics,similar metrics may be measured for subsystems or single devices withinthe platform. The reliability and availability metrics of a singledevice may impact the reliability and availability of a systemcontaining that device.

For example, if a storage system is physically contained within a singledatacenter, then the reliability of that storage system can be no betterthan the reliability of the datacenter. Thus, it may be worth investingheavily in physical plant and operations support to make that singledatacenter as robust as possible in order to increase reliability.However, applying such heavy investment across a large number ofdatacenters may be cost prohibitive. One solution to increasing dataavailability is to implement redundant storage systems (e.g., replicatedredundant storage systems and coded redundant storage systems) across adistributed computer system of less expensive (and less reliable)datacenters.

For example, FIG. 1 illustrates a communication system 100 in which oneor more storage systems 102 a or 102 b (generally 102) may be created,used, or managed. Storage system 102 may include any number or type ofhardware (together or alone with software) for storing data. Forexample, storage system 102 may comprise one or more datacenters 104.For example, FIG. 1 shows storages system 102 a including fourdatacenters 104 a-d. Other storage systems 102, such as storage system102 b, may have the same or different number of data centers 104. Inturn, datacenter 104 may comprise memory to store data. For example,datacenter 104 may include one or more servers 105, as shown fordatacenter 104 c. These servers 105 may be grouped together onto one ormore racks 106. The type and features of datacenters 104 may vary fromone another. For example, datacenter 104 a may have a different type ofmemory or a different amount of memory than datacenter 104 b. Similarly,each storage system 102 may vary from one another.

Datacenters 104 within a particular storage system 102 may beinterconnected via a first network connection 107. First networkconnection 107 may have a first set of parameters. For example, firstnetwork 107 may have minimum bandwidth or maximum latency requirements.First network 107 may be wired or wireless. First network 107 maycomprise cryptographically secured mechanisms, such as virtual privatenetwork (VPN) tunnels.

Communication system 100 may include a second network 108 for connectingstorage system 102 a (and datacenters 104) with one or more otherstorage systems 102, end devices 110, or other networks 112. In anaspect, second network 108 may comprise a provider network, a platformnetwork, or the like. Second network 108 may have a second set ofparameters, and the second set of parameters may be different than thefirst set of parameters.

Storage system 102 may be a redundant storage system. For example, thehardware and software of storage system 102 (e.g., data centers 104) maybe fallible. By storing data redundantly—such as by storing more thanone bit per bit of data, the extra bits may be used to reconstruct datathat may otherwise be lost due to failures of one or more data centers104, such as drive failures or other outages. As an example, storagesystem 102 may be a replicated redundant system that stores one or moreadditional full copies of each data object.

Additionally or alternatively, storage system 102 may be a codedredundant storage system—such as one that stores computed code bits thatmay be used to reconstruct lost data, such as by using algebraiccomputations. One advantage of a coded redundant system is that they maybe able to achieve higher reliability for a given amount of extrastorage space per object than replicated systems. On the other hand,replicated systems typically perform better (e.g., in operations persecond, throughput, and latency). These one or more additional copies orcoded bits may be stored according to a placement strategy.

A placement strategy may be a policy-controlled method for decidingwhere the stored data (e.g., including primary data and redundancy bits)are placed within storage system 102. For example, a placement strategymay incorporate a spread placement strategy or a partitioned placementstrategy. A spread placement strategy may randomly choose a subset ofthe drives (e.g., a subset of datacenters 104, servers 105, or racks106) and store each copy of an object on a distinct drive in the subset.In a spread placement strategy, there may be no alignment betweenreplicas of different objects. A partitioned placement strategy mayalign the replica sets of objects along boundaries of partitions, whichmay be groups of drives. In a partitioned placement strategy, no objectmay have replicas in more than one partition. Other placement strategiesinclude one-per-rack, one-per-host, rack-aware, copyset, andpartitioned-max-distributed.

FIG. 2 includes a flowchart of an exemplary method 200 for achievinghigh assurance storage within a system of multiple datacenters 104. Thereliability of method 200 may be controlled by a nonnegative integerparameter s. Parameter s may represent the number of extra replicas ofeach stored object. For example, method 200 having s equal zero may beless reliable than method 200 having s equal 1.

Method 200 may operate for a set of datacenters 104. The set ofdatacenters 104 may comprise k number of groups, and each group maycomprises number of datacenters 104. Each datacenter 104 may comprise dnumber of storage drives (e.g., racks 105).

At step 202, method 200 may include grouping datacenters 104 into kgroups. Optionally, the groups may be disjoint sets. For example, FIG. 1illustrates three groups (e.g., storage systems 102 a and 102 b).

As shown in FIG. 3, within each group (e.g., storage system 102) anumber of managers 302 may be deployed. Managers 302 may havefunctionality to read and write data in storage system 102, retrievedata from storage system 102, respond to queries for data stored instorage system 102 (including queries originating outside storage system102, Manager 302 may have functionality to implement a replicated orcoded redundancy, and it may allow placement strategy to be configureddynamically. Manager 302 may include a placement map 304 for storing andretrieving data. Manager 302 may also include functionality formonitoring data stored (or locations within) data storage system 102.For example, managers 302 shown in FIG. 3 each have three data monitors306 for monitoring storage system 102. For example, manager 302 may bean instance of Ceph or another application for implementing distributedstorage, such as Swift.

In an aspect, the number of managers 302 may equal at least s—that is,the number of datacenters 104 in storage system 102. For example, in theexemplary storage system 102 of FIG. 3, there are two datacenters—104 aand 104 b—and two managers 302 a and 302 b. Managers 302 may be deployedsuch that each datacenter 104 includes at least one manager 302.Further, within each manager 302, the number of data monitors 306 mayequal at least s+1. For example, FIG. 3 shows that each manager 302includes three data monitors 306.

Returning to FIG. 2, at step 204, a plurality of data monitors 306 maybe deployed. Each manager 302 may include at least one data monitor 306.Each data monitor 306 may be responsible for monitoring approximately1/(s+1) of drives 105 of each datacenter 104.

Returning to FIG. 2, at step 206, method 200 may include creating aplacement map 304 for each datacenter 102. For example, as shown in FIG.3 each manager 302 may comprise a placement map 304. Each placement map304 may dictate placement of data within datacenter 104 in which thatmanager 302 is deployed. Additionally or alternatively, placement map304 may dictate placement of data within other datacenters 104 ofstorage system 102. As discussed above, placement map 304 may dictatehow primary and secondary copies of data are stored in datacenters 104.For example, placement map 304 may dictate that all primary objectcopies are placed within datacenter 104 with which placement map 304 isassociated. Placement map 304 may dictate that secondary object copiesare placed one per member across the other datacenters 104 of thestorage system 102. For example, placement map 304 of manager 302 a maydictate that primary object data be stored in datacenter 104 a andsecondary object data be stored in datacenter 104 b, and placement map304 of manager 302 b may dictate that primary object data be stored indatacenter 104 b and secondary object data be stored in datacenter 104a.

Placement map 304 may have other policies or functionalities. Forexample, placement map 304 may dictate that the overall placementstrategy is partitioned. For example, object replica sets may be alignedwithin member sets of drives 105, such as s member sets of drives 105.In Ceph implementations of managers 302, placement map 304 may be acrush map.

Method 200 of FIG. 2 continues by storing data in storage system 102.This data flow is illustrated in FIG. 4. At step 208, method 200 mayinclude receiving a data object 402 to be stored in storage system 102.At step 210, method 200 may include creating at least one secondary copy(e.g., data object secondary copy 404), as illustrated by the COPY arrowin FIG. 4. The number of secondary copies 404 may be at least one lessthan the number of datacenters 104. For example, for the storage system102 of FIG. 3, the number of secondary copies 404 may be at least onesince the number of data centers 104 is equal to 2. As another example,if an exemplary storage system 102 included 14 datacenters 104, then thenumber of secondary copies 404 may be 13.

At step 212, method may include storing a primary copy of data object402 (e.g. data object 402)—as illustrated by the STORE arrow originatingfrom data object 402—in one of datacenters 104 and, in each of the otherdatacenters 104 of storage system 102, storing at least one of thesecondary copies 404—as illustrated by the STORE arrow originating fromdata object secondary copy 404. This storage may be done in accordancewith placement map 304.

Returning to FIG. 3, managers 302 may include different or additionalfunctionality for storing data in or retrieving data from datacenters104. The functionality of managers 302 may vary among managers 302. Forexample, managers 302 may manage data (e.g., data objects 402 andsecondary copies 404). This may include conducting read/writes to storeor retrieve data objects 402 or secondary copies 404. Each manager 302may use (s+1)-replication to replicate data objects 402. As anotherexample, each manager 302 may control a certain percentage of drives105.

For example, each manager 302 may control approximately 1/(s+1) ofdrives 105 in storage system 102. As an example, in storage system 102of FIG. 3, where s equals two, each manager 302 may control one-third ofdrives 105. Optionally, each manager 302 may control approximately1/(s+1) of drives 105 of each datacenter 104. For example, manager 302may control one-third of drives 105 of datacenter 104 a and one-third ofdrives 105 of datacenter 104 b. This control may be limited, forexample, to read/write actions, to dictating how data objects 402 andsecondary objects 404 are stored, or the like. Additionally oralternatively, this control may include deciding which datacenter 104hosts data object 402, and which data center 104 hosts secondary objects404. Additionally or alternatively, this control may include dictatingwhere the application or software using data object 404 is stored. Moregenerally, this control may control all aspects of the data stored inthose drives 105.

Each manager 302 may include one or more data monitors 306 that maymonitor the functionality of drives 105 or datacenters 104. Additionallyor alternatively, data monitors 304 may communicate with one another.

For example, each manager 302 may include at least (s+1) data monitors306. For example, as the exemplary storage system 102 of FIG. 3comprises two datacenters 104, each manager 302 may comprise three datamonitors 306 a, 306 b, and 306 c. Optionally, each data monitor 306 of agiven manager 302 may be running in each datacenter 104. For example, atleast one of data monitors 306 a, 306 b, and 306 c may be running indatacenter 104 a. Additionally, at least one other of data monitors 306a, 306 b, and 306 c may be running in datacenter 104 b. This isillustrated in FIG. 3 by the dashed lines illustrating which datamonitor 306 is running in which datacenter 104. For example, in thisexemplary embodiment, data monitor 306 a of manager 302 a and datamonitors 306 a and 306 b of manager 302 a may be running on datacenter104 a, and data monitors 306 b and 306 c of manager 302 a and datamonitor 306 c of manager 302 b may be running on datacenter 104 b.

Each data monitor 306 may manage drives 105 or datacenters 104. Thismanagement may include handling change or loss events that affect thedrives 105 or datacenters 104 within the purview of data monitor 306.For example, data monitor 306 may detect a change or loss event. Datamonitor 306 may take one or more actions in response to detecting changeor loss event.

For example, data monitor 306 may notify other data monitors 306 of thechange or loss event. Data monitor 306 may attempt to repair or undo thechange or loss event. Further, data monitor 306 may identify dataobjects 402 or secondary objects 404 that are inaccessible as a resultof the event. Data monitor 306 may also then identify the locations ofother copies of that inaccessible data, optionally by communicating withother data monitors 306. Data monitor 306 may redirect queries forinaccessible data to other locations where the data is stored. Datamonitor 306 may retrieve, through first network 107, another copy ofdata object 404 from another source in response to an outside query forthat data.

For example, FIG. 5 illustrates a method 500 for responding to a queryfor data object 402 (FIG. 4). At step 502, storage system 102 mayreceive a query for data object 402. This query may be received atdatacenter 104 in which data object 402 is stored. For example, a givendatacenter 104 may be responsible for providing all data to a specificapplication or subset of an application. Thus, data requests from thatapplication or other requestor may be directed to datacenter 104. Thequery for data object 402 may be received through a given networkconnection, such as second network 108.

At step 504, method 500 may include determining that the primary copy ofdata object 402 (e.g., data object 402) is inaccessible. Thisinaccessibility may be caused by a software or mechanical failure ofdrive 105 in which data object 402 is stored. To respond to the query,then, secondary copy data object 404 may be used.

At step 506, method 500 may include identifying a location of secondarycopy data object 404 based on placement map 304. The location ofsecondary copy data object 404 may be in the same datacenter 104 (e.g.,the same geographic location) in which the primary copy (e.g., dataobject 402) is located. Further, the location of secondary copy dataobject 404 may be in a different datacenter 104 than primary data object402.

At step 508, method 500 may include retrieving secondary copy dataobject 404 through first network 106. By using first network 106 (e.g.,VPN tunnel), to access secondary copy data object 404, rather than ahigher latency network connection (e.g., second network 108), latenciescan be reduced.

At step 510, method 500 may include communicating data based onsecondary copy data object 404 in response to the query via secondnetwork 108.

It will be understood that the terms and expressions used herein havethe ordinary meaning as is accorded to such terms and expressions bypersons of ordinary skill in the field of the present disclosure as setforth above, except where specific meanings have otherwise been setforth herein.

FIG. 6 is a block diagram of a network device 600 that may be connectedto or comprise a component system 100. For example, one or more ofdatacenters 104 or servers 105 may comprise network device 600. Networkdevice 600 may comprise hardware or a combination of hardware andsoftware.

The functionality to facilitate telecommunications via atelecommunications network may reside in one or a combination of networkdevices 600. Network device 600 depicted in FIG. 6 may represent orperform functionality of an appropriate network device 600, orcombination of network devices 600, such as, for example, a component orvarious components of a cellular broadcast system wireless network, aprocessor, a server, a gateway, a node, a mobile switching center (MSC),a short message service center (SMSC), an ALFS, a gateway mobilelocation center (GMLC), a radio access network (RAN), a serving mobilelocation center (SMLC), or the like, or any appropriate combinationthereof. It is emphasized that the block diagram depicted in FIG. 3 isexemplary and not intended to imply a limitation to a specificimplementation or configuration. Thus, network device 600 may beimplemented in a single device or multiple devices (e.g., single serveror multiple servers, single gateway or multiple gateways, singlecontroller or multiple controllers). Multiple network entities may bedistributed or centrally located. Multiple network entities maycommunicate wirelessly, via hard wire, or any appropriate combinationthereof.

Network device 600 may comprise a processor 602 and a memory 604 coupledto processor 602. Memory 604 may contain executable instructions that,when executed by processor 602, cause processor 602 to effectuateoperations associated with mapping wireless signal strength. As evidentfrom the description herein, network device 600 is not to be construedas software per se.

In addition to processor 602 and memory 604, network device 600 mayinclude an input/output system 606. Processor 602, memory 604, andinput/output system 606 may be coupled together (coupling not shown inFIG. 3) to allow communications therebetween. Each portion of networkdevice 600 may comprise circuitry for performing functions associatedwith each respective portion. Thus, each portion may comprise hardware,or a combination of hardware and software. Accordingly, each portion ofnetwork device 600 is not to be construed as software per se.Input/output system 606 may be capable of receiving or providinginformation from or to a communications device or other network entitiesconfigured for telecommunications. For example input/output system 606may include a wireless communications (e.g., 3G/4G/5G/GPS) card.Input/output system 606 may be capable of receiving or sending videoinformation, audio information, control information, image information,data, or any combination thereof. Input/output system 606 may be capableof transferring information with network device 600. In variousconfigurations, input/output system 606 may receive or provideinformation via any appropriate means, such as, for example, opticalmeans (e.g., infrared), electromagnetic means (e.g., RF, Wi-Fi,Bluetooth®, ZigBee®), acoustic means (e.g., speaker, microphone,ultrasonic receiver, ultrasonic transmitter), or a combination thereof.In an example configuration, input/output system 606 may comprise aWi-Fi finder, a two-way GPS chipset or equivalent, or the like, or acombination thereof.

Input/output system 606 of network device 600 may also contain one ormore network connections 608 that allows network device 600 tofacilitate communications between datacenters 102, devices 110, andnetworks, such as networks 107 or 108. Network connections 608 maycomprise communication media. Communication media typically embodycomputer-readable instructions, data structures, program modules orother data in a modulated data signal such as a carrier wave or othertransport mechanism and includes any information delivery media. By wayof example, and not limitation, communication media may include wiredmedia such as a wired network or direct-wired connection, or wirelessmedia such as acoustic, RF, infrared, or other wireless media. The termcomputer-readable media as used herein includes both storage media andcommunication media. Input/output system 606 also may include an inputdevice 610 for receiving user inputs, such as keyboard, mouse, pen,voice input device, or touch input device. Input/output system 606 mayalso include an output device 612, such as a display, speakers,vibration outputs, or a printer. For example, input/output system 606may include an IEEE 802.11-compliant transceiver. Optionally,input/output system 606 of device 600 may also include a transceiver forcommunicating with a cellular network, such as a core network, such asnetwork 107 or 108.

Processor 602 may be capable of performing functions associated withtelecommunications, such as functions for processing broadcast messages,as described herein. For example, processor 602 may be capable of, inconjunction with any other portion of network device 600, determining atype of broadcast message and acting according to the broadcast messagetype or content, as described herein.

Memory 604 of network device 600 may comprise a storage medium having aconcrete, tangible, physical structure. As is known, a signal does nothave a concrete, tangible, physical structure. Memory 604, as well asany computer-readable storage medium described herein, is not to beconstrued as a signal. Memory 604, as well as any computer-readablestorage medium described herein, is not to be construed as a transientsignal. Memory 604, as well as any computer-readable storage mediumdescribed herein, is not to be construed as a propagating signal. Memory604, as well as any computer-readable storage medium described herein,is to be construed as an article of manufacture.

Memory 604 may store any information utilized in conjunction withtelecommunications. Depending upon the exact configuration or type ofprocessor, memory 604 may include a volatile storage 614 (such as sometypes of RAM), a nonvolatile storage 316 (such as ROM, flash memory), ora combination thereof. Memory 604 may include additional storage (e.g.,a removable storage 618 or a nonremovable storage 620) including, forexample, tape, flash memory, smart cards, CD-ROM, DVD, or other opticalstorage, magnetic cassettes, magnetic tape, magnetic disk storage orother magnetic storage devices, USB-compatible memory, or any othermedium that can be used to store information and that can be accessed bynetwork device 600. Memory 604 may comprise executable instructionsthat, when executed by processor 602, cause processor 602 to effectuateoperations to store, retrieve, or query data from data storage system102.

The sequences and methods shown and described herein can be carried outin a different order than those described. The particular sequences,functions, and operations depicted in the drawings are merelyillustrative of one or more implementations of the present disclosure,and other implementations will be apparent to those of ordinary skill inthe art. The drawings are intended to illustrate various implementationsof the present disclosure that can be understood and appropriatelycarried out by those of ordinary skill in the art. Any arrangement,which is calculated to achieve the same purpose, may be substituted forthe specific examples provided.

Although the present disclosure has been described in connection withsome embodiments, it is not intended to be limited to the specific formset forth herein. Rather, the scope of the present disclosure is limitedonly by the accompanying claims. Additionally, although a feature mayappear to be described in connection with particular implementations,one of ordinary skill in the art would recognize that various featuresof the described examples may be combined in accordance with the presentdisclosure. In the claims, the term “comprising” does not exclude thepresence of other elements or steps.

Furthermore, although individually listed, a plurality of means,elements, or method steps may be implemented by or contained within asingle system, such as a single processor. Additionally, althoughindividual features may be included in different claims, these maypossibly be advantageously combined, and the inclusion in differentclaims does not imply that a combination of features is not feasible oradvantageous. Also the inclusion of a feature in one category of claimsdoes not imply a limitation to this category but rather indicates thatthe feature is equally applicable to other claim categories asappropriate.

Furthermore, the order of features in the claims do not imply anyspecific order in which the features must be worked, and, in particular,the order of individual steps in a method claim does not imply that thesteps must be performed in this order. Rather, the steps may beperformed in any suitable order. In addition, singular references do notexclude a plurality. Thus references to “a,” “an,” “first,” “second,” orthe like do not preclude a plurality.

While exemplary implementations of the systems and methods for datastorage have been described in connection with various computing devicesor processors, the underlying concepts can be applied to any computingdevice, processor, or system capable of facilitating initiation of acall to an emergency call center as described herein. The methods andapparatuses for data storage, or certain aspects or portions thereof,can take the form of program code (e.g., computer readable instructions)embodied in tangible storage media having a physical structure, such asfloppy diskettes, CD-ROMs, hard drives, or any other machine-readablestorage medium having a physical tangible structure (computer-readablestorage medium), wherein, when the program code is loaded into andexecuted by a machine, such as a computer, the machine becomes anapparatus for data storage. A computer-readable storage medium, asdescribed herein is an article of manufacture, and thus, not to beconstrued as a transitory signal or a propagating signal. In the case ofprogram code execution on programmable computers, the computing devicemay include a processor, a storage medium readable by the processor(such as volatile or non-volatile memory), at least one input device,and at least one output device. The program(s) can be implemented inassembly or machine language, if desired. The language can be a compiledor interpreted language, and combined with hardware implementations.

The methods and apparatuses for data storage may be practiced viacommunications embodied in the form of program code that is transmittedover some transmission medium, such as over electrical wiring orcabling, through fiber optics, wherein, when the program code isreceived and loaded into and executed by a machine, such as an EPROM, agate array, a programmable logic device (PLD), a client computer, or thelike, the machine becomes an apparatus for facilitating data storage.When implemented on a general-purpose processor, the program codecombines with the processor to provide a unique apparatus that operatesto invoke the functionality for data storage.

While the disclosed systems and methods for data storage have beendescribed in connection with the various examples of the variousfigures, it is to be understood that other similar implementations canbe used or modifications and additions can be made to the describedexamples for data storage. For example, one skilled in the art willrecognize that utilizing the data storage as described in the presentapplication may apply to any environment, whether wired or wireless, andmay be applied to any number of devices connected via a communicationsnetwork and interacting across the network. Therefore, the disclosedsystems and methods for data storage should not be limited to any singleimplementation, but rather should be construed in breadth and scope inaccordance with the appended claims.

What is claimed:
 1. A method comprising: identifying a datacenter grouphaving a number of datacenters (s), wherein each datacenter of the sdatacenters comprises a plurality of data monitors, wherein a number ofthe plurality of data monitors in each datacenter is equal to at leasts+1; for each datacenter of the datacenter group, creating a placementmap; receiving a data object to be stored in the datacenter group;creating secondary copies of the data object, wherein a number ofsecondary copies is equal to at least s−1; in accordance with theplacement maps, storing a primary copy of the data object in one of thedatacenters and, in each other of the datacenters, storing at least oneof the secondary copies; receiving a query for the data object;determining that the primary copy of the data object is inaccessible;based on the placement map, identifying a location of at least one ofthe secondary copies of the data object; replying to the query based atleast on the at least one of the secondary copies; and retrieving the atleast one of the secondary copies through a VPN tunnel.
 2. The method ofclaim 1, wherein the datacenters of the datacenter group areinterconnected via low-latency network connections.
 3. The method ofclaim 2, wherein the low-latency network connections comprise a virtualprivate network (VPN) tunnel.
 4. The method of claim 1, furthercomprising monitoring, via the plurality of data monitors, for a changeor loss of data within each of the datacenters.
 5. The method of claim1, wherein at least one of the datacenters comprises a lightweight datacenter.
 6. A system comprising: a first network; and a number ofdatacenters (s) interconnected via the first network; a data controllercommunicatively coupled to the first network, the data controllercomprising: an input/output for communicating via a second network; aprocessor communicatively coupled to the input/output; and memorystoring instructions that cause the processor to effectuate operationscomprising: for each datacenter of the s datacenters, creating aplacement map; receiving a data object via the second network; creatingsecondary copies of the data object, wherein a number of secondarycopies is equal to at least s−1; in accordance with the placement maps,storing a primary copy of the data object in one of the datacenters and,in each of the other datacenters, storing at least one of the secondarycopies, receiving, from the second network, a query for the data object;determining that the primary copy of the data object is inaccessible;based on the placement map, identifying a location of at least one ofthe secondary copies of the data object; and replying to the query basedon the at least one of the secondary copies; and a plurality of datamonitors for monitoring the s datacenters, wherein a number of theplurality of data monitors in each datacenter is equal to at least 1+s;wherein each of the s datacenters are located at geographically distinctlocations from one another.
 7. The system of claim 6, wherein the firstnetwork comprises a virtual private network (VPN).
 8. The system ofclaim 6, wherein the operations further comprise: receiving, from thesecond network, a query for the data object; based on the placement map,identifying a location of the primary copy of the data object;retrieving, via the first network, the primary copy from the location;and transmitting, via the second network, a reply to the query based onthe primary copy.
 9. The system of claim 6, wherein each of the sdatacenters stores at least one of the plurality of data monitors. 10.The system of claim 6, wherein a latency of the first network is lowerthan a latency of the second network.
 11. A method comprising: receivinga data object for storage in a storage system, the storage systemcomprising a number of datacenters (s) interconnected by a firstnetwork; creating secondary copies of the data object, wherein a numberof secondary copies is equal to at least s−1; in accordance with aplacement map of at least one of the datacenters, storing a primary copyof the data object in one of the datacenters and, in each other of thedatacenters, storing at least one of the secondary copies; monitoring,via a plurality of data monitors, an accessibility of data stored in thestorage system, the data including the primary copy and the secondarycopies of the data objects; receiving, from a second network, a queryfor the data object; based on the placement map, identifying a locationof the primary copy of the data object; retrieving, via the firstnetwork, the primary copy from the location; and transmitting, via thesecond network, a reply to the query based on the primary copy; andwherein a number of the data monitors is equal to at least s+1.
 12. Themethod of claim 11, further comprising: based at least on themonitoring, detecting, by a monitor of the plurality of monitors, anevent affecting the accessibility of the primary copy; communicating, bythe monitor, to at least one other monitor of the plurality of datamonitors, wherein the at least one other monitor is associated with asecond datacenter of the datacenters, wherein at least one of thesecondary copies of the data object is stored in the second datacenter;receiving, by the monitor, a transmission based on the at least one ofthe secondary copies from the second datacenter; and transmitting areply to the query based at least on the transmission.
 13. The method ofclaim 11, wherein a latency of the first network is lower than a latencyof the second network.
 14. The method of claim 13, wherein the firstnetwork comprises a virtual private network (VPN).
 15. The method ofclaim 11, wherein at least one of the data monitors is a Ceph instance.